The Frogs of Toro Canyon Creek

This past August OWCN was activated for an oil event at Toro Canyon Creek.  For those who may be unfamiliar with the area as I had been, it’s a creek in the hills just north of Carpinteria. A year-round water source was created after an oil-water separator had been built back in the 1990’s to help contain an existing oil well seepage.  This allowed the oil to be diverted to a tank and the separated water to feed the creek.  When clean, I can imagine how incredible this small oasis could be and the wildlife it would support; however, when we were activated, much of it was filled with thick oil sludge.

Toro Canyon Creek

While the initial animals recovered were found deceased in the oiled creek, we soon began recovering live animals, all of which belonged to 2 species of frogs (plus one Western fence lizard who happened to be in the wrong place during cleanup).  These frog species, the Baja California Treefrog (Baja) and the California Treefrog are often found to be sympatric (found in the same geographic area with each other) in southern California.


Baja California Treefrog

The Baja California Treefrog was by far the most recovered at this event (89 out of 94 frogs).  Prior to 2006, it was classified under one species known as the Pacific Treefrog, but was then separated into 3 separate species with the southernmost population becoming the Baja California Treefrog.  

The name “Treefrog” isn’t very accurate as these frogs are more ground-dwellers of low shrubs and grasses, although like treefrogs they have the typical rounded toepads that make them excellent climbers.

Baja California Treefrog variations

It is a small frog up to 2 inches long that has many different color and pattern variations which can change in response to its background environment.  The one distinguishing characteristic that does not change is the dark stripe that runs across the eyes.  It is an ambush predator that feeds mostly on insects at night, waiting for prey to come its way before lunging and capturing with its sticky tongue.  

During the breeding season from November to July, the frogs are found close to water sources, with the males becoming territorial.  The male makes his calls usually at night to attract females, but sometimes during the day as well during peak breeding season.  It is the most commonly heard frog in its range and the call (click to hear) that has been widely used in movies.


California Treefrog

The lower recovered number of the other species, the California Treefrog, could have been attributed to their different preferred habitat.  This species prefers boulder areas of which there was much less of.  I would always be excited when we’d recover one of these because of the small area they inhabited, in hopes that we could help preserve their presence after the cleaning had been completed.

This frog is just a tad larger in size than the Baja.  It has less color variation with a lighter brownish grey mottled pattern on top and a rougher skin texture with bumps on its back similar to toads you may be familiar with but having those rounded toepads of treefrogs.  The lack of the eye stripe is the best way to tell them apart from the Baja; however, they sometimes can have a faint stripe, which in juveniles may be more distinct.

California Treefrog

This frog prefers mostly boulder type areas for refuge and tends to move further away from water during fall and winter, becoming less active during the colder months.  During the spring they return to the areas of water to breed but usually take 2 years to reach a reproductive age compared to just 1 for the Baja.


Observations from the Field

One interesting oil-related observation that was made during this event is that regardless of how oiled the frog may have been when captured, this visible oil almost immediately would slough away with its slime layer.  Further investigation hopefully will be done on how much oil remains on them that cannot be seen and the effect on amphibians both short and long term.

Duane

Way Down South

For this week’s blog, I’d like to highlight a region you are familiar with but perhaps not in terms of OWCN or the wildlife that is found there. Region 5, the “South Coast” region is the most urbanized region of California, having the top 3 populated counties. Recall that the California Department of Fish and Wildlife (CDFW) divides the state into 7 functional regions:

  • Region 1: Northern
  • Region 2: North Central
  • Region 3: Bay Delta
  • Region 4: Central
  • Region 5: South Coast
  • Region 6: Inland Deserts
  • Region 7: Marine

Region 5 consists of the counties along the coast from Santa Barbara down to San Diego, also including the offshore islands in those areas.  

There are 13 Member Organizations in this region: 

  • Santa Barbara County
    • Channel Islands Marine & Wildlife Institute
    • Santa Barbara Zoo
    • Santa Barbara Wildlife Care Network
    • Channel Islands Cetacean Research Unit
  • Los Angeles County
    • California Wildlife Center
    • International Bird Rescue (South)
    • Marine Mammal Care Center
    • Aquarium of the Pacific
  • Orange County
    • Wetlands & Wildlife Care Center
    • Pacific Marine Mammal Center
  • San Diego County
    • Sea World San Diego
    • Project Wildlife
    • National Marine Mammal Foundation

This region tends to be drier that most of the others, resulting in more drought-tolerant species and isolated populations of the moisture-dependent amphibians.  Still, there is an abundance of amazing wildlife particularly in the non-urbanized areas.  Let’s cover the profiles of a few that I find particularly interesting.

Coast Range Newt 

This colorful subspecies of the California Newt is a Species of Special Concern endemic to the coast and coastal mountains from Mendocino County south to San Diego County.  It inhabits wet forests, oak forests, chaparral, and rolling grasslands.  This amphibian is terrestrial and diurnal as an adult but aquatic when breeding and uses the same breeding sites throughout its life.

While it is understood among wildlife rehabilitators to watch out for beaks, teeth and claws/talons, this tiny animal can actually kill you.  Adults secrete tetrodotoxin on their skin, the same toxin found in pufferfish. Whenever I hear “tetrodotoxin” I always think of Homer Simpson eating Fugu and his eventful drive home. However, the actual initial signs of toxicity are a tingling, burning and numbing sensation of the lips and tongue, followed by numbness of the face and extremities and eventually leading to death due to respiratory failure.  

Light-footed Ridgway’s Rail

This rail is one of the most endangered shorebirds in California.  Federally and State Endangered as well as CDFW Fully Protected, this bird frequents coastal wetlands from Southern California into Baja California.  

It is pretty easy to distinguish from other rails in that it is large and robust (like an athletic chicken) with a rust-colored neck and breast, barred flanks, and a long, mostly orange beak, particularly the mandible.  Still, you may not see it often because of its reclusiveness and tendency to stay hidden in the dense marsh vegetation.  When threatened it also acts like a chicken in that it often prefers to run rather than fly or swim.

Ringtail

Although the Ringtail inhabits all regions, it is an uncommon small mammal that is rarely seen.  This nocturnal carnivore has a special interest to me because when I first started in wildlife rehabilitation I had not known there were populations in the Santa Monica Mountains until I saw a couple that had been hit by cars along Malibu Canyon Road.  A little while after we noticed them we were fortunate to rehabilitate one at the facility I worked.  Some time later,  while searching for a Golden Eagle one evening in Malibu Creek State Park, we came across a large group of them!

The Ringtail is a peculiar looking animal that perhaps not many of you knew existed in California. They are found in riparian and rocky areas, using hollow trees or large rock landscape for cover. They are listed by CDFW as Fully Protected after their numbers significantly declined due to trapping for their pelts.  

Bald and Golden Eagles

Although less common to Region 5, both the Golden and Bald Eagles can be found here.  Both species of this magnificent raptor are listed as Fully Protected by CDFW, with the Bald Eagle also listed as State Endangered.  They are the two largest raptors in California (excluding the California Condor for those who consider that a raptor). The juvenile Bald Eagle can also sometimes be mistaken for a Golden Eagle, as they are similar in coloration.

Even though they can look similar at certain life stages, these two species differ in many ways.  The Golden Eagle frequents open foothills and mountain regions, preying on mammals; while the Bald Eagle prefers areas next to larger water sources for fish.  Haviing worked with both species, I have found that they also differ greatly in temperament.  The Golden is a very cool and collected customer that will tolerate extended periods of care and handling.  The Bald, on the other hand, is the extreme opposite, very easily stressed and one that would be difficult to rehabilitate for an extended period of time.

San Clemente Loggerhead Shrike 

This shrike is a subspecies endemic to San Clemente Island.  It is darker in coloration than other subspecies but can easily be differentiated simply by the location it is found. It frequents lowlands and foothills with open areas and scattered places for perching and surveying for prey.  I also find shrikes in general to be somewhat fascinating in how they skewer their prey on sharp objects for feeding or caching, although that may be a bit morbid.  

This bird is both Federally Endangered and a CDFW Species of Special Concern.  At one point it was believed to be the most endangered animal in North America.

Most of my time living in California was spent in Los Angeles County, for my veterinary internship, working overnight emergency and then at the California Wildlife Center.  It was where I received most of my experience with wildlife. The common species found there are often quite different from other regions, mostly due to the dry climate and their tolerance of urbanization but each and every region has an amazing diversity of species that can be appreciated.

Duane